An organic light-emitting device including: a plurality of first electrodes that are respectively patterned according to first, second, and third sub-pixels; a second electrode facing the plurality of first electrodes; a plurality of emission layers between the plurality of first electrodes and the second electrode; a hole transport region between the plurality of first electrodes and the plurality of emission layers; and at least one selected from a first auxiliary layer and a second auxiliary layer. The first auxiliary layer may be between the hole transport region and the first emission layer, the second auxiliary layer may be between the hole transport region and the second emission layer, and at least one selected from the first auxiliary layer and the second auxiliary layer may include a first compound represented by Formula 1: